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Ultrastructural features of mast cell activation were studied in degenerative/reparative experimental model of mechanically damaged lymph-heart striated muscle during the first postoperative week. 24 h after damage, the intracytoplasmic empty degranulation channels were revealed in a certain part of resident and circulating mast cells (MCs) located near the site of injury. These findings are evidence that previously ther was activation and secretory response of MCs by a process known as compound exocytosis which involves not only granule- to-plasma membrane fusions and formation of degranulation channels. We have found rare MCs showing release of single. altered, membrane-free granules into the space restricted by the plasma membrane of mature resident MCs and the basal lamina surrounding them. During the fist postoperative week we have more commonly observed activated lymph-heart MCs with prominent intragranular changes characterized by diminishing of electron-dense component of granules and loss of granule matrix. We have also revealed close association of some unaltered and altered secretory granules with completely or partially empty degranulation channels that permeate the mast cell cytoplasm. Some of these channels remained open directly to the exterior of the cells. It is not improbable that these findings provide the ultrastructural basis for potential discharge of small amounts of granule mediators into the open channels (incomplete exocytosis) duding partial degranulation of activated in vivo frog MCs. Immunocytochemical staining for histamine of activated frog MCs showed the presence of the immunoreactive material both in unaltered and altered cytoplasmic granules. As a rule, gold particles were located over residual electron-dense component of altered granule, whereas little or no gold particles were revealed over the swollen matrix. Ultrastructural features of secretory granule formation in the cytoplasm of some MCs were observed toward the end of the first postoperative week. Electron-microscopic autoradiography has shown that replicative and transcriptional activity of MCs is not observed in the studied postoperative period. No mitoses in MCs have been revealed in this period. A few mast cells were found in necrosis. Taken together, our results indicate that MCs are one the first cell types that respond to injury of lymph-heart striated muscle and release a variety of preformed mediators, including histamine. These findings suggest that activated MCs play an important role in the initiation of an inflammatory process during repair of damaged lymph-heart striated muscle.

Mast cells (MCs) were studied quantitatively and qualitatively in the wall of the esophagus (upper, middle and lower portions) of the individuals in the I period of mature age (22-35 years, n = 6) as well as in old and senile persons (61-82 years, n = 10). In all the individuals, the total number of MCs was found to increase from the upper portion of the esophagus towards the lower one. Within the esophageal wall, the total number of MCs decreased in the direction from tunica mucosa towards adventitia. During I period of mature age, the resting MCs filled with granules predominated, while the degranulating MCs were located in the lower esophageal segment. In the individuals of old and senile age, the degranulating MCs were more frequently observed in the upper and lower esophageal segments.

Electron microscopic observations of the lymph hearts of tadpoles and yearling frogs of Rana temporaria showed that mast cells (MCs) were present not only between muscle fibers (population of resident MCs), but in the cavities of lymph heart (population of circulating MCs), too. There were some differences in the ultrastructure of the resident MCs at each studied stage of larval development. The first recognizable MCs were revealed in the lymph hearts at premetamorphosis (stages 39-41). MCs presented as mononuclear relatively small and slightly elongated cells with a few immature secretory granules and numerous free ribosomes, polysomes and short cisternae of rough endoplasmic reticulum (RER) in the cytoplasm. Chromatin of their nuclei was poorly condensed; the Golgi apparatus was moderately developed. At pro-metamorphosis (stages 44-45), we revealed MCs at different levels of their differentiation. Some MCs demonstrated an active process of granulogenesis in their cytoplasm. Among densely packed cytoplasmic organelles, immature secretory granules were closely associated with cisternae of RER and free ribosomes. Other MCs appeared as more differentiated cells. They were characterized by a predominantly heterochromatic nuclei and cytoplasm filled with polymorphic and heterogeneous granules. MCs also showed a reduction in the number of free ribosomes and cisternae of RER in the cytoplasm. On the contrary, the Golgi apparatus was well developed. Stacks of Golgi cisternae, detaching vacuoles, and progranules occupied the perinuclear region. The majority of the outlines above ultrastructural features of differentiated MCs were typical for MCs of yearling frogs. At metamorphic climax (stages 52-53), MCs often tightly contacted with macrophages. We did not reveal apoptotic MCs. However, some MCs exhibited morphological features typical for programmed necrosis-like death, which was characterized by mitochondria swelling, dilatation of cisternae of RER and nuclear envelope, plasma membrane rupture and subsequent loss of intracellular contents. Electron microscopical immunocytochemistry revealed the localization of atrial natriuretic peptide (ANP), substance S (SP) and heat shock protein (Hsp70) in the secretory granules of the resident and circulating MCs at different stages of tadpole development and in yearling frogs.

To identify clinico-laboratory symptoms and pathogenetic factors of overactive bladder syndrome (OBS), we used cytochemical analysis of peripheral blood lymphocyte enzymes in 88 males and females aged 50-75 years with this syndrome (70 patients) and control (18 subjects). Biopsy of the anterior wall of the bladder with examination of detrusor myocytes was made in 28 of 70 patients. OBS patients were found to have reduced aerobic respiration in blood lymphocytes and detruzor cells, dystrophy and atrophy of myocytes, moderate interstitial cell infiltration of the detrusor in increasing number and activity of mast cells, T-lymphocytes (CD4, CD8) and macrophages (CD11). We came to the conclusion that development and symptoms of OBS are caused by low energetic activity of the detrusor in line with dysfunction of the bladder mast cells and immunity factors. This is important for diagnosis of OBS severity and choice of energotropic therapeutic measures.

Mast cells (MCs) of the "blood" and lymph hearts of the adult frog Rana temporaria were investigated at histochemical and ultrastructural levels. Two populations of MCs were revealed in these propulsative organs: population of resident MCs and population of circulating MCs. It has been shown that the resident cardiac MCs have an oval or elongated form and are located between atrial or ventricular myocytes and under endocardial endothelium. The resident cardiac MCs are situated in connective tissue of epicardium, too. Avascular myocardium of the frog ventricle consists of a spongy network of muscle trabeculae. We revealed circulating MCs in intertrabecular spaces and clefts of the spongy myocardium and in the blood of the main central cavity. Circulating MCs are round in shape and contain a large central nucleus enriched with condensed chromatin. They resemble the lymphocytes, but show cytoplasm filled with granules. These granules ultrastructure is much like that of the granules of the cardiac resident MCs. In the lymph heart, oval and somewhat elongated resident MCs are located in the interstitial space among cross-striated muscle fibers and among smooth muscle cells of tubular (afferent and efferent) valves. Sometimes lymphocyte-like circulating MCs are revealed in the cavity of lymph heart. Circulating MCs are also present in the lymphatics located adjacent to the lymph hearts. In certain parts of the lymphatic walls MCs are in close adhesion to the mesothelial cells lining the lymphatic cavity. Our histochemical investigation revealed that both the resident and circulating MCs of the propulsative organs give a strongly positive reaction with alcian blue, but weakly red with safranin and weakly metachromatic with toluidine blue. The presence of population of circulating MCs in the frog suggests that there are differences in biology of MCs between lower and higher vertebrates.

It is known that many heart diseases are accompanied by a significant increase in the level of atrial natriuretic peptide (ANP), a regulator of cardiovascular homeostasis, in the pericardial fluid. Cellular sources of ANP in pericardial cavity remain uncertain. By EM immunocytochemistry, we have examined the presence and localization of ANP in rat and human pericardium. ANP-immunoreactive material was revealed in granules of mast cells (MCs) situated in connective tissue of the pericardium. MCs have an oval form and measure about 6.5 x 12.5 and 9.1 x 13.6 microm in the rat and human pericardium, respectively. Density of MC population makes up about 50 and 10 cells/mm2 in the rat and human pericardium, respectively. Our data suggest possible participation of the pericardial MCs in endocrine function of pericardium and in control of the ANP level in pericardial cavity.

Anterior urinary bladder wall biopsy specimens were examined in 24 males and 4 females, aged 52 to 76 years, who had been suffering from the hyperactive urinary bladder for 1-10 years. Increases in the number and activity of interstitial mast cells and their degranulation and the symptoms of chronic immune inflammation were revealed. Neuromuscular spastic dysfunction of the detrusor is considered to result from the activation of mast cells.

One hundred twenty eight patients with irritated bowel syndrome (IBS) were included in the study and divided into two equal groups. Group one consisted of patients with type II IBS (without atrophic changes in the colon mucosa, CM); group II consisted of patients with type II IBS (with atrophic changes in the CM); the control group consisted of 24 practically healthy individuals. All the subjects, including the healthy ones, were examined using clinical, endoscopic, immunohistochemical methods, and electron microscopy. The study found that the development of type IIBS was connected with hyperplasia and hyperfunction of serotonin-producing cells with intensification of apoptosis. The number of colonocytes with nuclei that are immunopositive to D1 cycline increases, and the number of colonocyte nuclei that are immunopositive to proliferating cell nuclear antigen decreases. The onset of type II IBS is associated with hyperplasia and hyperfunction of all apudocyte populations, including those producing melatonin and serotonin, and simultaneous reduction of the number and functional exhaustion of VIP-producing and mast cells. Colonocyte apoptosis intensifies; their proliferative potential decreases.

With immunochemical assay, the expression of B-amyloid and tau-protein in the mast cells of the stomach and skin was first detected in patients with Alzheimer's disease (AD), which supports the hypothesis that AD is a systemic disease involving different organs and tissues. Verification of expression of two key peptides that participate in the pathogenesis of AD in the samples of extra-brain tissues allows B-amyloid and tau-protein to be regarded as promising markers and mast cells to be considered to the most suitable object for lifetime diagnosis of neurodegenerative diseases.

It was shown by light and electron microscopy that local exposure of the projection of the MC-8 lao-gun acupuncture point in rat pad to low-intensity (0.05 mW/cm2) extremely high-frequency (42.0 GHz) electromagnetic radiation caused a degranulation of derma mast cells. It was suggested that the response of skin mast cells is an important amplifying mechanism in the chain of events leading to a systemic response of the organism to low-intensity electromagnetic radiation.

Aim: To study functional morphology of a total population of endocrine cells of colon mucosa, mast and enterochromaffine cells., Materials and Methods: Light and electrone microscopy, immunohistochemical methods, morphometry were used to study endocrine and mast cells of the sigmoid colon in inflammation., Results: Changes of functional morphology and size of endocrine and mast cell population as well as apudocytes producing serotonin, melatonin, vasointestinal peptides were stated. Apudocyte and mass cell functional morphology, clinical symptoms and mucosal structural changes correlated. Specificity of some parameters in Chron's disease is shown., Conclusion: The results may provide additional criteria in diagnosis of different variants of chronic colitis.

The aim of this study was assessment of the role of mast cells in inflammatory processes associated with keratoconus and corneal epithelial-endothelial dystrophy and clinical assessment of Lecrolin, a specially designed dosage form (eye drops) of potassium cromoglycate (intal) used as an antiallergic drug in asthma, rhinitis, etc. Examinations of 43 biopsy specimens of the conjunctiva from patients with keratoconus and epithelial-endothelial corneal dystrophy demonstrated the significance of immune inflammation in the pathogenesis of these diseases. Mast cells are a typical cell element participating in inflammation at all stages. The count of mast cells increases from 2.5 during the acute stage to 8.86 during the chronic stage, which is explained by absence of the leukocytic stage and proteolysis and stabilization of mature labrocyte degranulation associated with it. Reactions of mast cells with lymphocytes and monocytes/macrophages lead to proliferation of fibroblasts and chronic development of collagen formation. Close relationships between microvessels and mast cells promote stable spasms of the vessels, impairing the microcirculatory bed and leading to ischemia of the anterior segment of the eye. In such cases sodium cromolyne drugs (lecrolin) inhibiting histamine release and stabilizing mast cell membranes are recommended.

Using specific M-cholinoblockers the response of rat pulmonary and mediastinal pleural mast cells to acetylcholine was studied. Acetylcholine was established to cause their massive degranulation which is prevented by preliminary administration of atropin or bromide ipratropium. Electric current stimulation of the vagal nerve caused similar reaction in mast cells. The transection of vagal nerve inferior to ganglion nodosum augmented the synthesis of specific granules in mast cells, although blocked their cytosis. Acetyl cholinestherase reaction demonstrated axons in pleura, while electron microscopic studies revealed terminals containing cholinergic synaptic vesicles on mast cells. A conclusion was made concerning functional interaction between mast cells and vagal nerve axons.

It was shown that doxorubicin influenced the morphofunctional state of the peritoneal, mesenteric and dermal tissue basophils which was evident from changes in the total number of the mast cells and the level of their maturity, activity and ability to respond to con A and the antigen. In the late periods after the completion of the treatment with the cytostatic the quantitative changes were slightly pronounced and the functional activity remained high for 3 months. Predisposition to allergic reactions was confirmed by positive intracutaneous tests with horse serum albumin.

Inflammatory, degenerative and neurocirculatory disturbances in the intestine of children suffering from colibacillosis was followed by pronounced immune reactions: the number of IgG-, IgM- and IgE-containing cells increased and that of IgA-containing cells decreased, the number of enteroendocrinocytes and labrocytes changed. Progressing disturbances of blood circulation enhanced trophic changes of the mucosa, resulting in various complications. The data obtained allowed us to distinguish the syndrome of capillary-trophic insufficiency in the patho- and morphogenesis of colibacillosis.

Membrane structures of the mast cells are mainly of protein nature, since trypsin treatment causes almost complete loss of mast cell ability to form rosettes. Trypsin-sensitive proteins have no critical role in the formation of membrane thymocytes structures, which cause their affinity to the mast cells. Sialic acids play a role in organization of the membrane thymocyte structures.

Histochemical and electron-microscopic studies of skin biopsy specimens from 65 patients with mastocytosis have enabled the authors to classify the various mastocytoses (on the basis of infiltrate topography and structural features of mast cells) into macular, pustular, and nodular varieties of cutaneous mastocytosis (urticaria pigmentosa) and mastocytoma. No differences in mast cell structure were detected between cutaneous and systemic mastocytoses. Electron microscopically, mast cells in both appeared normal, with a predominance of granules having a fine-grained or homogeneous matrix and a small number of lamellar structures. In mastocytomas, on the other hand, ultrastructural changes and considerable degranulation were observed in the mast cells.

Mast cells reaction in the wall of the normal fallopian tubes has been studied morphometrically in 48 women subjected to the operation for a uterine myoma and ovarian retention cyst. It has been stated that volume and degree of the mast cell degranulation depends on the menstrual cycle phase, age and part of the fallopian tube. The changes of the mast cells reaction correlate with the capillary diameters in the ampulla and the isthmus of the oviduct. Labrocytes participate in regulation of the microcirculatory blood stream of the fallopian tubes.

Mucous membrane ultrastructure was studied after extracorporeal perfusion of the small intestine under auto- (12 experiments), allo- (10 experiments) and xenotransplantations (4 experiments). In all mucosal structures the lesions are demonstrated to depend on nonspecific factors on the one hand, and on genetically foreigh tissue, on the other hand. In every experimental group, the earliest changes occur in microcirculatory bed. Disorders in vessel and blood flow tone lymphotasis and interstitial edema result in disturbances of capillary-epithelial interrelations and metabolic processes. Destructive changes are followed by tissue neutrophilosis, activation of macrophages and plasmocytic cells, degranulation of eosinophil, enterochromaffin and mast cells, profound mucin excretion. Unlike autoperfusion, alloperfusion is characterized by massive neutrophillic degranulation and more severe lesions of mucosal structures. At allotransplantation, neutrophil cell reaction (nonspecific by its nature) is supposed to be the earliest and primary in the course of establishing transplantation immunity. At xenotransplantation, intestinal destruction, developing and rapidly progressing, is connected with the influence of natural antibodies.

In adult dogs and white Wistar rats, relationships between the automonic nerve endings, mucosal endocrine cells, mast cells, and blood capillaries in the gastric wall were studied with the aid of electron microscopy. A close association of 3 components of the regulatory mechanisms: neural, hormonal, and humoral, in the form of the triad comprising endocrine cells, autonomic nerve endings, and blood capillaries, was revealed, with no true synapses between them. Accumulations of the granules of the endocrine cells, synaptic vesicles of the autonomic nerves, and the pinocytose vesicles of the capillary endothelium were seen at inner surface of the cells' membranes which is the morphological indication of the physiological function. The data obtained suggest that the interaction between the 3 above components is realised through the diffuse synapses, and indicate that the interstitium of the digestive tract wall is the area of integration of the neural and the hormonal links of neuro-homoral visceral reflexes.

Labrocytes situated in the external tunica of the cat basis cerebri arteries have been studied by means of Falck's method and electron microscopically. It has been stated that dilated areas in islets of the mast cells, having ultrastructure peculiar for actively secreting formations, are situated at the distance of 80-100 nm from the smooth muscle cells of the middle tunica. Close structural and functional relations have been found to exist between the adventitial labrocytes and neural conductors of the arteries. Participation of the arterial mast cells in mechanisms of local selfregulation is supposed.

On studying the surface of intact and cryogenic masto- and lymphocytes by the scanning electron microscopy the formation of close membrane contacts was detected between thymocytes and mast cells looking in vitro as mastolymphocyte rosettes (ML-rosettes). During ML-rosette formation changes in cell surface organization were observed. Availability of viable thymocytes is necessary for ML-rosette formation. The surface topography of cells constituting the ML-rosettes is seen changing during rosette formation. It is proposed that the mastocyte may function as an acceptor acquiring immunological specificity through the contact with lymphocytes whose membrane responds actively towards the antigen by changing its surface. Reorganization of the lymphocyte plasma membrane may be perceived by mastocytes as a signal of granule secretion.

The influence of trophoblast-specific beta 1-glycoprotein (TSG) on the degranulation of mast cells and their saturation with heparin was studied. Introduction of the TSG into the population of mast cells of the rat peritoneal fluid practically does not change their degranulation, but lowers the degree of their saturation with heparin. An antibiotic alone increases the saturation of the cells with heparin. The serum of an allergic animal markedly stimulates the degranulation and lowers the degree of saturation of the mast cells with heparin. In an experimental model (antibiotic--the serum of the allergic mast cells) the mast cells transform into very clear (heparin-free) cells and the degree of saturation is at minimum. The TSG introduction into this system stabilizes the population of mast cells and markedly increases the degree of their saturation with heparin. Although the degranulation is rather intensive, it is less expressed, than in the experimental model. This suggests the presence of TSG receptors on the mast cells (targets of allergic reactions). The possibility to use TSG preparations in the therapy of allergic diseases is discussed.

The test of indirect degranulation of rat mast cells was applied to the study of the specific activity of 16 series of noninfectious allergens from domestic dust (3 series) from hotel dust (7 series) and from the pollen of fescue (6 series). The concentration of protein nitrogen in the allergens from the domestic and hotel dust constituted to 10 000 PNU, and in the allergen from the pollen of fescue--125 000, 50 000, 15 000 and 7 000 PNU. In studying the specific activity of domestic allergens use was made of the sera of patients suffering from bronchial asthma with a marked allergy to domestic dust sera of patients with pollinoses with a marked allergy to fescue pollen was applied to the study of the specific activity of pollen allergen. For the assessment of the indirect degranulation test in mast cells of rats an index of mast cell degranulation of rats (IMCDR) was employed. It was shown that the IMCDR values were equal to 0.46, 0.58, 0.62 in using the domestic dust and in the case of the hotel dust - from 0.17 to 0.28. The mean values for the group of preparations from the domestic dust were 2.5 times greater than for the group of preparations for the hotel dust and were 0.55 and 0.22, respectively. For the allergen from the fescue pollen the IMCDR values varied from 1.23 to 0.16, and increased with the rise of the protein nitrogen concentration (PNU). Additional studies demonstrated that the specific activity of the domestic dust allergen with the crude sera and with those preserved in frozen condition for 3 to 6 months was almost the same. The results obtained permit to draw a conclusion that the method of indirect degranulation of rat mast cells with trizing of commercial batches of infectious allergens.

Dynamics of ultrastructure of mast cells (MC) and that of the capillaries of the derma have been studied by means of electron morphometry methods in rats during pre- and postnatal ontogenesis. The dynamics of the Golgi complex volume, that of the mitochondria and specific granules have been calculated in the total volume of the MC membrane organelles. Certain new data have been obtained on the process of the MC specific granules formation in the derma from progranules up to the stage of a mature granule. The process mentioned is most intensive during the first weeks of the postnatal ontogenesis. At the age of two weeks, signs of an active exocytosis of the granules are noted. Judging by certain morphological signs, development of transendothelial transport of substances in capillaries takes place in parallel with formation of the specific granules and corresponds to the beginning of exocytosis of substances in the MC granules. The correlative analysis proves that formation of the MC specific granules is connected with the number of microvesicles in cytoplasm of endotheliocytes.

The article summarizes the latest literature data on the morphology of the granulation tissue cells: neutrophils, monocytes, macrophages, mast cells and fibroblasts. In the majority of cases these cells were studied with the help of such methods as electron microscopy, histochemical analysis autoradiography. Sources of origin of these cells and dynamics of their development in the period of formation and maturation of the granulation tissue are considered. Findings of the current studies into the structure and functions of fibroblasts and their role in collagen formation, as well as the role of hormonal factors in these processes are analysed in detail.

Blastolysin is shown to cause degranulation of mast cells, resulting in a reduction of their histamine content and in their release of mediators that activate eosinophilic leukocytes (EL). These accelerate the deamination of the histamine released by mast cells to the extracellular medium. It is possible that blastolysin acts directly on EL granules which are largely responsible for histamine inactivation.

A chronic 90-day inhalation of polyethylsiloxane fluid at a concentration of 10 and 2 mg/m3 produced local irritation and general toxic effect on rats. Local irritation induced catarrhal-desqueamative tracheitis that was accompanied by a microfocal interstitial process in the lungs. The general toxic effect gave rise to interstitial myocarditis that was followed by focal cardiosclerosis and dystrophic lesions of vascular walls and areas of liver parenchyma. Changes in the thymus-lymph system and adrenal structure suggested prolonged protective tension of the animal body. A chronic 90-day inhalation of polyethylsiloxane at a concentration of 0.2 mg/m3 brought about no pathological lesions in the microstructure of animal organs.

A rationale for sequential immunohistochemical studies of the endocrine function of APUD cells is described, as exemplified by a study of serotonin-containing cells in rat small intestine, involving preparation of paraffin and semithin sections of epoxide resin-embedded tissue, followed by electron-microscopic examination of cells detected by the immunoperoxidase technique. With the approach described, it has been shown that a positive immunohistochemical reaction to antiserotonin antiserum is given, along with EC cells, by those mast cells disposed in groups near the EC cells as well as among connective-tissue cells of villi under the basement membrane. It is suggested that by collecting and accumulating the serotonin synthesized by specialized EC cells, mast cells transport it to sites of utilization as required by the specific arrangement.

The most essential features of the mast cell are continuous production (and partially also absorption from the environment), deposition, and secretion of the two groups of biologically active substances of the regulatory type: heparin and other acid clycosaminoglycanes, and also histamine and, probably, other biogenic amines. These substances are antagonists and have an influence on the homeostasis of the microregion (capillary-connective tissue-parenchyma) -- the main area of action of the mast cells. The mast-cell population is characterized, as compared with other cellular populations of the microregion, by a smaller size, greater morphological and functional diversity, functional duality (capability of producing both a positive and negative effect), and therefore possesses a number of essential properties the biological regulator should meet. The system of mast cells differs from the regulators of a higher order (the nervous and endocrine system) by a smaller radius of action and a greater simplicity of the structure, the latter manifests itself in equality of all its components. The conclusion is drawn that mast cells may be considered as the regulators of tissue homeostasis and a last link in the general reaction of adaptation at the cellular level.

Ultrastructural alterations in mast and plasma cells of pregnant rat liver were studied in the initial period of endotoxin shock. A significant increase in functional activity of mast and plasma cells and the presence of intercellular contacts and contacts with cells of perisinusoidal space were found. The data obtained suggest that endotoxin stimulates connective tissue cells, leading to the release of mediators and biologically active substances responsible for hepatic injury during endotoxemia.

Ultrastructure of chromaffin, mast and pigment cells has been studied in Liza soiuy, Rana temporaria, Testudo horsfieldi, guinea pig, cat, as well as in human fetuses at the age of 7-28 weeks of intrauterine development. Correlative connections of the vegetative neural fibres and mast cells have been revealed by means of Falck's method in guinea pigs, given noradrenaline, rausedil and histamine, and in Testudo horsfieldi, given acetylcholine. The chromaffin cells differ from the mast and pigment cells by extremely small granules. In Liza soiuy and in Rana temporaria the granule-containing cells present in all arterial membranes. It contributes to direct regulatory influence on various elements of the vascular wall. In other animals and in man these cells are situated mainly in adventitia and affect smooth arterial myocytes. The vegetative neural transmitters and the granule-containing cells make a single for regulating system.

The Falk-Hillarp method was used to study circadian activity of the rat dura mater mast cells and the content of monoamines in them. The quantitative changes in the mast cells are described as time-dependent. The data obtained were statistically analyzed to disclose the latent periodicity of the processes occurring in the mast cells. A twenty-four-hour cycle of the cell activity was discovered. Two functional states of the mast cells were distinguished: (a) the maximum of degranulating mast cells was recorded at noon; (b) the maximum of intact fat cells was seen at 3 p. m.

During the intermediate period of endotoxin shock in dogs, endothelial cells were isolated and the slides with desquamated endotheliocytes were explored. Besides, a study was made of the ultrastructure of the arterioles and sinusoidal capillaries of the liver. A six-fold increase in their quantity in the slides was established and the pattern of alterations in the vessels of varying diameter was specified. It is assumed that in the mechanism of injury a definite role is played by the direct action of endotoxin and biologically active substances.

Mast cells and vascular permeability were examined in experimental aseptic peritonitis induced by intraperitoneal injection of starch into rats. It was established that derangement of vascular permeability in the inflammatory focus was consequent on degranulation of mast cells and release of inflammatory mediators. The model of the inflammation suggested enables the local focus to be created, with no mast cells seen for a long period of time (at least for 3 weeks).

The heterokaryons of undifferentiated mouse fibroblasts (L and 3T3-4E/TK-) and various cell elements of the rat peritoneal exudate were obtained under the treatment with inactivated Sendai virus. The reactivation of RNA and DNA synthesis in the nuclei of highly differentiated periotoneal exudate cells and the synthesis of thymidine kinase controlled by the nuclei of peritoneal exudate cells were shown to occur in the heterokaryons. During the process of reactivation, the ring-like nuclei of polymorphonuclear leucocytes acquired the form characteristic of the reactivated nuclei of mononuclears. The morphological changes of heparin-containing granules in the cytoplasm of the heterokaryons of mast cells and undifferentiated fibroblasts suggest the degeneration and breakdown of granules.